Vaultz Locking Index Card File with Flip Top Holds 450 4 x 6 Cards, Black, Sold as 1 Each Vaultz? black locking index card file has a reliable key lock, steel corners, aluminum reinforcement and felt interior. Heavy-duty file safely holds index cards. Sturdy key lock keeps contents secure. Aluminum trim reinforcements plus chrome steel corners provide additional security. Soft felt interior.